Investigating the molecular basis of sex reversal in sequential hermaphroditic fishes

Most plants and animals irreversibly differentiate becoming either males or females. However, in some groups, notably fishes, individuals begin life as one sex and reverse sex sometime later in response to social cues (sequential hermaphrodism).

Sex reversal in sequential hermaphrodites is complete,  entailing radical restructuring of the gonad, alterations in morphology, and modifications to behaviour.

The molecular basis of this stunning transformation is unknown, but is of intense interest, not only as a means to enhance our understanding of sex determination and differentiation, cellular commitment and tissue re-engineering, but also as a spectacular example of phenotypic plasticity in response to environment.

Kaj Kamstra holding a small spotty wrasse female.
Kaj Kamstra holding a small spotty wrasse female.

Using the ubiquitous NZ spotty, we will undertake a series of experiments to understand spotty social behaviour and cognitive abilities (individual recognition, transitive inference, winner-loser effects) to investigate how female spotty determine social hierarchy and if dominant females are molecularly primed for sex change. We will identify components of the neuroendocrine and genetic pathways underlying this stunning transformation. We will also undertake experimental manipulations to produce a time series of samples taken during the process of sex reversal, and couple these with state-of-the-art gene expression analyses and comparative genomic approaches, to identify both the primary trigger and subsequent genetic cascade that results in female-male sex reversal in these fishes.

Currently involved in this project are Postdoctoral Fellows Dr. Chloé van der Burg and Dr. Kaj Kamstra, and also newly arrived PhD student Haylee Quertermous.

Kaj Kamstra (left), Haylee Quertermous (middle) and Chloé van der Burg (right) fishing for spotties in Tauranga, with Mount Maunganui as a backdrop.
Kaj Kamstra (left), Haylee Quertermous (middle) and Chloé van der Burg (right) fishing for spotties in Tauranga, with Mount Maunganui as a backdrop.

Collaborators

Dr. Culum Brown (Macquarie University)

Dr. Erica Todd (Deakin University)

Dr. Simon Muncaster (University of Waikato)

Prof. Christine Jasoni (University of Otago)